Various constructions are known for molded plastic closures for use with bottles and like containers. While one-piece constructions are known, optimum sealing is ordinarily achieved through the use of two-component or composite constructions, including an outer, relatively hard closure cap or shell, and an inner, relatively soft and pliable sealing liner. For example, U.S. Pat. No. 4,378,893, to Wilde et al., U.S. Pat. No. 4,407,442, to Wilde et al., and U.S. Pat. No. 4,497,765, to Wilde et al., hereby incorporated by reference, illustrate a composite closure construction including an outer closure cap, and a sealing liner formed in situ within said closure cap, wherein the sealing liner forms a top/side seal with an associated container (i.e., the closure includes both generally downwardly facing and generally inwardly facing sealing surfaces).
U.S. Pat. No. 4,658,976, to Pohlenz, hereby incorporated by reference, illustrates another form of closure including a relatively pliable sealing liner, with this closure including a so-called insert liner. In this construction, a preformed, disc-shaped liner is inserted into a molded closure shell, with the liner being urged into sealing engagement with an associated container when the closure assembly is placed thereon. Notably, the closure of this patent includes an annular shoulder at the juncture of the top wall and skirt portions of the closure cap, which shoulder cooperates with the sealing liner to form a top/side seal with an associated container.
While closures including an insert liner can be desirably economically manufactured, previous constructions have nevertheless suffered from certain design deficiencies. Because the inwardly facing side seal of this type of closure is formed generally along the vertical extent of the annular shoulder at the juncture of the top wall and skirt portions, the sealing contact with a container is not always sufficiently localized and concentrated for optimum sealing in all applications. Additionally, the relative cross-sectional mass of this annular shoulder can detract from efficient closure formation, since this mass of plastic material is relatively slow to cool during molding. Heretofore, closures of this type having insert liners have not been configured to abate undesired inadvertent dislodgement of the liner attendant to removal of the closure from a container. Dislodgement can occur because the diameter of the disc, after removal from a container, is sometimes significantly less than the diameter of the disc when it is initially inserted. Naturally, dislodgement of the liner can impair the sealing integrity of the closure.
The present invention is directed to a closure assembly, including a sealing insert liner, which is configured to provide enhanced sealing performance and improved liner retention, and which promotes high-speed manufacture.